Primary amine-thiourea grafted graphene-based heterogeneous chiral catalysts for highly enantioselective Michael additions
Küçük Resim Yok
Tarih
2022
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Heterogeneous asymmetric catalysis based on earth-abundant carbon materials put together the advantages for the ease of separation, simple regeneration, and high stability of solid catalysts as well as acts as low-cost, environmentally friendly metal-free alternative to the metal-based catalysts. Two new bifunctional carbocatalysts [(S,S) and (R,R) GO-PATU] were prepared by anchoring enantiomerically pure organosilanes bearing primary amine and thiourea groups to the graphene oxide (GO) skeleton covalently via silane coupling reaction. The surface modification of GO was analyzed by a combination of Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM) techniques. The catalytic performances of graphene-based materials were investigated in the asymmetric Michael addition reactions of alpha,alpha-disubstituted-aldehydes to nitrostyrenes and N-substituted-maleimides. The effects of solvents and Bronsted basic or acidic additives were evaluated using both catalysts and good yields (up to 85%) and stereoselectivities (up to 95% ee) were obtained in dichloromethane at room temperature in the presence of L- and D-camphorsulfonic acid. Besides, recycling and reusing studies of the catalysts were successfully performed.
Açıklama
Anahtar Kelimeler
Metal-Free Asymmetric Catalysis, Heterogeneous Catalyst, Bifunctional Carbocatalyst, Graphene Oxide, Asymmetric Michael Addition
Kaynak
Molecular Catalysis
WoS Q Değeri
Q2
Scopus Q Değeri
Q2
Cilt
526
